Measuring and controlling wound-in tension for web winding machines

ABSTRACT

A web winding machine including a driver drum and a web roll and means for urging the web roll against the driver drum to form a nip therebetween. The web material is carried over a portion of the surface of the driver drum, between the nip, and around the web roll. A complete loop of the web material is formed from the nip, around a measuring roll, and around the web roll. A load cell senses the tension on the web at the measuring roll and generates a signal which is compared with an ideal desired tensioning signal for generating a difference signal. The difference signal is then utilized to control the web pressure and hence the web tension, and to bring the web tension into accord with the desired tension. An initial slow run of the web is provided with the adjusted nip pressure being recorded on a chart as a function of the instantaneous diameter of the web roll. The chart or program thus produced is then used at high speeds in subsequent winding operations to directly control the nip pressure and hence the web tension.

United States Patent Pfeiffer Aug. 29, 1972 [54] MEASURING AND CONTROLLING WOUND-IN TENSION FOR WEB WINDING MACHINES [72] Inventor: John D. Pfeifler, Downingtown, Pa.

[73] Assignee: Beloit Corporation, Downingtown,

22 Filed: Dec. 12,1969

21 App1.No.: 884,519

[52] US. Cl. ..242/65, 242/66, 242/75.1, 242/75.51

[51] Int. Cl. ..B65h 17/08, B65h 17/12 [58] Field of Search.....242l75.l, 75.41, 75.51, 56 A, 242/67.1, 67.5, 65, 66, DIG. 1; 346/1 Primary Examiner-George F. Mautz Assistant ExaminerGregory A. Walters Att0rneyHill, Sherman, Meroni, Gross & Simpson e5 1104 ur/au cauurse [57] ABSTRACT A web winding machine including a driver drum and a web roll and means for urging the web roll against the driver drum to form a nip therebetween. The web material is carried over a portion of the surface of the driver drum, between the nip, and around the web roll. A complete loop of the web material is formed from the nip, around a measuring roll, and around the web roll. A load cell senses the tension on the web at the measuring roll and generates a signal which is compared with an ideal desired tensioning signal for generating a difference signal. The difference signal is then utilized to control the web pressure and hence the web tension, and to bring the web tension into accord with the desired tension. An initial slow run of the web is provided with the adjusted nip pressure being recorded on a chart as a function of the instantaneous diameter of the web roll. The chart or program thus produced is then used at high speeds in subsequent winding operations to directly control the nip pressure and hence the web tension.

9 Claims, 4 Drawing Figures Patented Aug. 29, 1972 3,687,388

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MEASURING AND CONTROLLING WOUND-IN TENSION FOR WEB WINDING MACHINES BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The field of art to which this invention pertains is a web winding machine and in particular to a means for measuring and controlling the web tension during the winding of a web on a roll and to automatically feed nip pressure information to a nip control device in accordance with an optimum pressure schedule.

SUMMARY OF THE INVENTION It is an important object of the present invention to provide a means for controlling the wound-in tension for a web winding machine by sensing the instantaneous tension on the web after the web has passed through the nip and by correcting for deviations in the instantaneous tension from a desired prescheduled tension requirement.

It is also an object of the present invention to provide a meansfor programming the nip pressure in a web winding machine such that the loading of a web roll against a driver roll can be instantaneously adjusted to accommodate changes in roll diameter in accordance with a predetermined desired web tension schedule.

It is an additional object of this invention to provide a method for controlling the nip pressure and hence the wound-in tension of a continuously winding web and simultaneously developing a program of nip pressure vs. diameter for controlling subsequent winding operations at comparatively higher speeds.

It is an additional object of this invention to provide a web winding machine including a driving roll and a web roll and a web passing between the nip of the rolls and forming a single closed loop around both a measuring roll and the web roll wherein a load cell is utilized to sense the tensioning on the web as determined by the measuring roll, and wherein the output of the load cell is compared with a desired web tensioning schedule for generating an error signal to control the nip pressure and to generate program means for subsequent high speed winding operations.

It is an additional object of this invention to provide a means for programming the nip pressure for a web winding machine in accordance with the changing diameter of a winding web on a web roll wherein an initial program winding operation is carried on at a relatively slow speed, and subsequent automatic winding operations are controlled at substantially higher speeds.

It is a further object of this invention to provide a means for measuring the tension of a winding web during an entire winding operation and for comparing the measured tension with a prescheduled preset tension for generating an error signal and for further integrating the error signal to control the nip pressure of the winding machine.

It is also an object of this invention to provide a web winding machine as described above wherein a pro gram tape is developed which programs the changing nip pressure as a function of the number of revolutions of one of the winding rolls of the web winding machine.

These and other objects and advantages of the present invention will be understood in greater detail from the following description and the associated drawings wherein reference numerals are utilized in designating the illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic illustration of a web winding machine in accordance with the present invention;

FIG. 2 is a diagrammatic illustration of another embodiment of a web winding machine utilizing the features of the present invention;

FIG. 3 is a diagrammatic illustration showing the high speed operation of the web winding machine of FIG. 1 utilizing a tape program control in accordance with the present invention, and

FIG. 4 is a diagrammatic illustration of the web winding machine of FIG. 2 as employed during subsequent high speed winding operations.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A web winding machine according to the present invention includes a driver roll 10 and a web roll 11. Means are provided to rotate the driver roll 10 in the direction indicated by the arrow 12, and such a rotation causes an opposite rotation of the web roll 11 as indicated by the arrow 13.

The web roll 11 is carried on a core 14 which in turn is slidably movable on parallel rails 15. The core 14 is initially a blank about which a web is wound. As the diameter of the resulting roll increases, the roll 14 slides along the rail 15 while continually bearing against the driver roll 10.

A web 16 is passed over the upper portion 17 of the driver roll 10 and passes between the rolls l0 and l l at a nip 18. The web then wraps about the roll 11 and continues to do so until the diameter of the roll 11 has increased to the proper size whereupon the fed web is severed, and pick-up means are provided to remove the roll 11 and insert a substitute blank core. The severed web is then reapplied to the surface of the new core, and the winding operation repeats.

Normally, the web 16 passes between the nip l8 and is wound tightly about substantially 360 of the roll 11. However, in the case of the present invention, the web 16 passes between the nip 18 and continues as at 19 to be wound about a measuring roll 20 and a further tuming roll 21 to be subsequently wrapped about the web roll 11 at a contact line 22.

The extension of the web 16 as at 19 from the nip 18 to the contact line 22 may be said to be a continuous loop. This loop provides a means for measuring the tension on the web roll 11.

As will be well understood to those skilled in the art, the tension of the web on the web roll 11 will be a function of several factors such as the type of paper involved, the relative diameters of the driving drum and the web roll and most importantly of the nip pressure between the rolls. It has been found that by properly varying the nip pressure, the tension on the web at the region 19 can be adequately controlled to produce the desired winding function.

In the embodiment shown in FIG. 1, the nip pressure between the rolls and 11 is developed by means of a loading arm 23 which has an end face 24 which acts directly on the core 14 to bias the web roll 11 into surface engagement with the winder drum 10. The loading arm 23 is pivoted at a base 25 and is loaded into the biasing condition by means of an air spring 26 or the like.

It has been found that optimum nip pressure and hence optimum web tension varies as a function of diameter of the web roll 11. Also, the desired loading of the web roll 11 varies as a function of the quality and thickness of the web material 16 being wound. Since the nip pressure varies not only as a function of winding diameter, but also as a function of web type material, it would be highly desirable to find a means to automatically program the nip pressure for each type web as the diameter of the wind increases. Such a means is provided in the present invention in the form of a means for measuring and simultaneously controlling the nip pressure for each web type matter, and at the same time registering the amount of control required in accordance with the revolution rate of the winding operation.

In particular, a load cell 27 is secured by means of a coupling 28 to the measuring roll 20. The web in the region 19 is wrapped about the measuring roll 20 such that the portion 19 and a further portion 29 are substantially parallel whereby the angle of wrap about the measuring roll 20 is substantially constant, and whereby maximum sensitivity to web tension is achieved for the load cell 27.

The load cell 27 generates a signal which is proportional to the instantaneous tension on the web in the region 19. The signal is coupled by means of a line 30 to a preset device 31. Essentially, the preset device 31 is a difference or error signal generator which generates a signal which is the difference between the input or load cell signal and a preset signal as indicated by the arrow 32. Information is fed into the preset device'31 at the input 32 which reflects the desired tension of the web in the region 19 as a function of the diameter of the roll 11. This preset or desired signal is compared to the actual or instantaneous signal as developed by the load cell 27 and is fed to a proportional band or circuit integrating device 33 via a coupling line 34. The integral of the signal as received from the device 33 is fed to the air motor 26 or the like to control the loading pressure of the loading arm 23 on the core 14.

Accordingly, the combination of the measuring roll 20, the load cell 27, the error signal generator 31 and the transducer 26 comprise a closed loop system for sensing, comparing, and correcting the loading of the rolls l0 and 11.

Simultaneously with the controlling of the loading pressure applied to the loading arm 23 from the transducer 26, the adjusted nip pressure signal as applied to the transducer is also applied via a coupling 35 to a tape punch station 36. A standard tape punch 37 then records along its continuously moving surface, the nip pressure required to be applied to the transducer 26 to produce the desired web tension in the region 19. To coordinate the information applied to the tape 37 via the coupling line 35, means are provided to register on the tape, information which reflects and registers the amount of feed of the web 16 which has taken place at any instance of time.

In particular, a revolution counter 38 is provided to sense the number of revolutions of the driving drum l6 and to feed the counted output through a line 39 to the tape punch station 36. Accordingly, the tape 37 will have applied to the surface thereof information which reflects the nip pressure required to produce the desired web tensioning as a function of the number of revolutions and hence of the diameter of the web roll In the alternative, charts could be made of the nip pressure using an x-y recorder. This would produce 'a visual indication of variations in nip pressure. The charts could be then used with a curve follower to reproduce the required nip pressure during subsequent runs.

In accordance with the present invention, the above described measuring and recording operation is intended to be utilized only in connection with an initial run of a new type of web material. For this purpose, the

entire winding operation may be operated at a substantially lower than normal speed to assure the proper operation of the control parameters. Once, however, the tape 37 is programmed, the measuring function can be eliminated, and the program tape can be utilized to directly control the loading of the transducer 26, and the winding machine may be operated at a substantially higher winding speed.

The high speed winding operation for the web winding machine of FIG. 1 is shown in FIG. 3. In particular, the load cell 27 and preset device 31 along with the proportional device 33 have been eliminated. The tape 37 is then fed into a tape playback device 40 where the recorded information is transposed into a pressure signal 41 for controlling the loading of the transducer 26. The feed of the tape 37 is controlled into the tape playback device 40 by means of a revolution counter 42 which generates a signal at a coupling line 43 indicative of the revolution count of the winder drum 10. For instance, for each subsequent wind of the drum 10, the tape 37 is fed a discrete distance into the tape playback device 40, and the loading signal is generated for controlling the loading of the transducer 26 to affect the nip pressure and hence the web tension on the surface of the web roll 11. It is noted that the web 16 is wound continuously about the web roll 11, and the loop as indicated at 19in FIG. 1 is no longer required.

An alternate embodiment of the present invention is shown in FIG. 2 wherein a web roll 44 is driven by a pair of driver drums 45 and 46. A web 47 passes around the rolls 45 and 46 and forms a pair of nips at 48 and 49, respectively. The web 47 passes as at 48 around a measuring roll 49a and against the inner surface of a turning roll 50 to be wrapped about the outer surface of the web roll 44.

As in the case of the winding machine shown in FIG. 1, the turning roll is disposed to maintain substantial parallel relationship between the approaching and unrolling portions of the web. A load cell 50 is coupled to the roll 49a and generates an output signal at 51 which is in turn fed to an error or difference signal generator 52. An input 53 is also fed to the difference signal generator 52 and reflects the desired tensioning schedule for the web 47 in the region 48 as a function of changing diameter of the web roll 44.

A difference signal is generated at the output 54 of the difference signal generator 52 and is fed to a controller or integrator 55 which integrates the signal and applies the same through a line 56 to a loading device 57 for a rider roll 58. The loading device 57 controls the nip pressure developed between the rolls 45, 46 and the web roll 44.

Also, the signal which is utilized to actuate the loading device 57 is also coupled through a line 59 to a program recorder 60 which records on an X-y recorder or the like the continuous applied loading information as a function of the changing diameter of the web roll 44. The program or revolution count information may be fed into the program recorder 60 at an input 61. The information 61 may be either as a function of the number of revolutions of one of the drums 44, 45 or 46 or may be a function of the total linear footage travel of the moving web 47. Regardless, it is only necessary that means be provided in the program recorder for registering the loading information of the loader 57 in accordance with the increasing diameter of the roll 44.

With the information recorded in the program recorder 60 at a lower speed as in the case of the web winding machine of FIG. 1, the web winding machine of FIG. 2 may be subsequently utilized at higher speeds as shown in FIG. 4.

In particular, a program playback 62 is utilized to develop a signal at a coupling line 63 which reflects the recorded loading information and to playback the information in accordance with a specific drum program as provided by a program device 64. The program device 64 may be any device which gears the playback of the loading information in accordance with the travel of the moving web 47, as, for instance, in the case of the use of the revolution counter in FIGS. 1 and 3. The information thus played back is used to control the loading device 57 which in turn regulates the loading of the rider roll 58 and controls the nips 48 and 49 between the web roll 44 and the two driver drums 45 and 46.

It will be apparent to those skilled in the art that various combinations and modifications of the features of this invention may be readily accomplished without departing from the spirit and scope of features described herein, and I desire to claim all such modifications and combinations as properly come within the field of my contribution to the art.

I claim as my invention:

1. The method of controlling the wound-in tension on a web winding machine comprising the steps of: driving a web roll into a rotary motion with another roll, thereby forming a nip between the driving and driven rolls, passing a web between the nip and around the web roll, forming a loop of web material intermediate the nip and the initial line of wrap of the web about the web roll, measuring the instantaneous tension on the winding web within said loop, comparing the measured tension with a desired tension for the winding web, and integrating the difference between the instantaneous measured tension and the desired tension and utilizing the integrated difference tension to regulate the nip pressure between the driving and driven drums to stabilize the actual web tension at the desired tension for the winding web.

2. The method of controlling the wound-in tension on a web winding machine as described in claim 1 including the steps of:

recording the adjusted instantaneous nip pressure,

utilizing in subsequent winding operations, the recorded nip pressure to directly adjust the nip pressure between the driving and driven drums.

3. In a web winding machine including a winder drum and a web roll being urged against the winder drum to form a nip therebetween wherein a web is passed through the nip for being wound on the web roll, a wound-in tension control device comprising:

a web roll about which a web is to be wound,

said winder drum forming a nip with the web roll,

a measuring roll spaced from the web and the turning rolls,

a web traversing a path which passes from a position against said winder drum to and through said nip, then to a loop around the measuring roll, from the loop to and around said web roll and thereafter returning through said nip, the path of the web from the loop to and around the web roll being free of any additional nips,

sensing means for monitoring the tension applied to the measuring roll by the moving web, and control means for adjusting the nip pressure in accordance with the deviation of the output of said sensing means from a prescheduled norm.

4. A wound-in tension control device in accordance with claim 3 wherein a turning roll is positioned against the web to urge the portion of the web leaving the measuring roll into a path which is substantially parallel to the path of the web approaching the measuring roll whereby the sensitivity of said sensing means is maximized for detecting variations in the tension of the web.

5. A wound-in tension device in accordance with claim 3 wherein said sensing device includes a load cell having a signal output indicative of the tension of the measuring roll by the moving web,

a preset device for generating a prescheduled signal indicative of the desired loading of the measuring roll by the moving web,

a difference signal generator,

means for applying the output signal from the load cell and the prescheduled signal to said difference signal generator,

actuator means utilizing the output of the difference signal generator to regulate nip pressure between the winder drum and the web roll.

6. A web winding machine comprising:

a winder drum,

a web roll,

pressure means urging said web roll against said winder drum and forming a nip thereby such that said web roll is driven by said winder drum,

a web passing around a portion of the surface of said winder drum through the nip and around the web roll said web having a loop formed intermediate the nip and the initial point of wrap of the web on the web roll said web roll then returning through said nip, for

being wound on said web roll,

the path of the web from the loop to and around the web roll being free of any additional nips,

a measuring roll inserted in the 'loop and having a surface portion thereof urged against the tension of the moving web,

load sensing means coupled to the measuring roll and generating a signal indicative of the tension of the web on the measuring roll, control means, means for presetting a signal into the control means indicative of the instantaneous desired tensioning of the web on the measuring roll,

means coupling the output of the load sensing means into said control means,

said control means generating an error signal indicative of the deviation of the output of said load sensing means from said preset signal,

transducer means utilizing said error signal to adjust the nip pressure between the winder drum and web roll.

7. A web winding machine in accordance with claim 6 wherein said transducer means comprises a rider roll and means responsive to said error signal for urging said rider roll against the surface of the web roll to regulate the nip pressure between the winder drum and the web roll.

8. A web winding machine comprising:

a winder drum,

a web roll,

pressure means urging said web roll against said winder drum and forming a nip thereby such that said web roll is driven by said winder drum,

a web passing around a portion of the surface of said winder drum, through the nip and around the web roll,

said web having a loop formed intermediate the nip and the initial point of wrap of the web on the web roll for being wound on said web roll and then returning through said nip, the path of the web from the loop to and around the web roll being free of any additional nips,

a measuring roll inserted in the loop and having a surface portion thereof urged against the tension of the moving web,

load sensing means coupled to the measuring roll and generating a signal indicative of the tension of the web on the measuring roll,

control means,

means for presetting a signal into the control means indicative of the instantaneous desired tensioning of the web on the measuring roll, I

means coupling the output of the load sensing means into said control means,

said control means generating an error signal indicative of the deviation of the output of said load sensing means from said preset signal,

counter means for measuring the distance traveled by the web during the course of the winding of the web on the web roll,

gprogram recorder means rrst ransducer means utilizing said error signal to adjust the nip pressure between the winder drum and the web roll,

second transducer means utilizing said error signal to generate a continuous record at said program recorder means of the adjusted nip pressure, and

means for coupling the output of said counter means to said program recorder means for registering the length of web wound on the web roll substantially simultaneously with the registering of the adjusted nip pressure at said program recorder means.

. 9. A web winding machine in accordance with claim 2 wherein said recorder means comprises an x-y recorder which records the adjusted nip pressure as a continuous curve on an x-y chart. 

1. The method of controlling the wound-in tension on a web winding machine comprising the steps of: driving a web roll into a rotary motion with another roll, thereby forming a nip between the driving and driven rolls, passing a web between the nip and around the web roll, forming a loop of web material intermediate the nip and the initial line of wrap of the web about the web roll, measuring the instantaneous tension on the winding web within said loop, comparing the measured tension with a desired tension for the winding web, and integrating the difference between the instantaneous measured tension and the desired tension and utilizing the integrated difference tension to regulate the nip pressure between the driving and driven drums to stabilize the actual web tension at the desired tension for the winding web.
 2. The method of controlling the wound-in tension on a web winding machine as described in claim 1 including the steps of: recording the adjusted instantaneous nip pressure, utilizing in subsequent winding operations, the recorded nip pressure to directly adjust the nip pressure between the driving and driven drums.
 3. In a web winding machine including a winder drum and a web roll being urged against the winder drum to form a nip therebetween wherein a web is passed through the nip for being wound on the web roll, a wound-in tension control device comprising: a web roll about which a web is to be wound, said winder drum forming a nip with the web roll, a measuring roll spaced from the web and the turning rolls, a web traversing a path which passes from a position against said winder drum to and through said nip, then to a loop around the measuring roll, from the loop to and around said web roll and thereafter returning through said nip, the path of the web from the loop to and around the web roll being free of any additional nips, sensing means for monitoring the tension applied to the measuring roll by the moving web, and control means for adjusting the nip pressure in accordance with the deviation of the output of said sensing means from a prescheduled norm.
 4. A wound-in tension control device in accordance with claim 3 wherein a turning roll is positioned against the web to urge the portion of the web leaving the measuring roll into a path which is substantially parallel to the path of the web approaching the measuring roll whereby the sensitivity of said sensing means is maximized for detecting variations in the tension of the web.
 5. A wound-in tension device in accordance with claim 3 wherein said sensing device includes a load cell having a signal output indicative of the tension of the measuring roll by the moving web, a preset device for generating a prescheduled signal indicative of the desired Loading of the measuring roll by the moving web, a difference signal generator, means for applying the output signal from the load cell and the prescheduled signal to said difference signal generator, actuator means utilizing the output of the difference signal generator to regulate nip pressure between the winder drum and the web roll.
 6. A web winding machine comprising: a winder drum, a web roll, pressure means urging said web roll against said winder drum and forming a nip thereby such that said web roll is driven by said winder drum, a web passing around a portion of the surface of said winder drum through the nip and around the web roll, said web having a loop formed intermediate the nip and the initial point of wrap of the web on the web roll, said web roll then returning through said nip, for being wound on said web roll the path of the web from the loop to and around the web roll being free of any additional nips, a measuring roll inserted in the loop and having a surface portion thereof urged against the tension of the moving web, load sensing means coupled to the measuring roll and generating a signal indicative of the tension of the web on the measuring roll, control means, means for presetting a signal into the control means indicative of the instantaneous desired tensioning of the web on the measuring roll, means coupling the output of the load sensing means into said control means, said control means generating an error signal indicative of the deviation of the output of said load sensing means from said preset signal, transducer means utilizing said error signal to adjust the nip pressure between the winder drum and web roll.
 7. A web winding machine in accordance with claim 6 wherein said transducer means comprises a rider roll and means responsive to said error signal for urging said rider roll against the surface of the web roll to regulate the nip pressure between the winder drum and the web roll.
 8. A web winding machine comprising: a winder drum, a web roll, pressure means urging said web roll against said winder drum and forming a nip thereby such that said web roll is driven by said winder drum, a web passing around a portion of the surface of said winder drum, through the nip and around the web roll, said web having a loop formed intermediate the nip and the initial point of wrap of the web on the web roll for being wound on said web roll and then returning through said nip, the path of the web from the loop to and around the web roll being free of any additional nips, a measuring roll inserted in the loop and having a surface portion thereof urged against the tension of the moving web, load sensing means coupled to the measuring roll and generating a signal indicative of the tension of the web on the measuring roll, control means, means for presetting a signal into the control means indicative of the instantaneous desired tensioning of the web on the measuring roll, means coupling the output of the load sensing means into said control means, said control means generating an error signal indicative of the deviation of the output of said load sensing means from said preset signal, counter means for measuring the distance traveled by the web during the course of the winding of the web on the web roll, a program recorder means, first transducer means utilizing said error signal to adjust the nip pressure between the winder drum and the web roll, second transducer means utilizing said error signal to generate a continuous record at said program recorder means of the adjusted nip pressure, and means for coupling the output of said counter means to said program recorder means for registering the length of web wound on the web roll substantially simultaneously with the registering of the adjusted nip pressure at said program recorder means.
 9. A web winding machine in accordance with claim 2 wherein said recoRder means comprises an X-Y recorder which records the adjusted nip pressure as a continuous curve on an X-Y chart. 